When you flip the parts over you can see there is a lot more to the CD player. The circuit board has 4 main processors and on the drive assembly there are the mechanical parts along with more electronics.
Unfortunately none of these parts are repairable. NuTone does sell a CD player Repair kit f just for the IMA4406. If you have an early IM4406 there isn't any way to fix a non-working CD player.